Diseases in the oral cavity include dental caries, periodontal diseases, such as gingivitis and periodontitis, stomatitis, and the like. Among them, the dental caries is a representative disease of teeth, which is developed due to the dissolution of dentine by an acid produced by microorganisms in the oral cavity. Among the microorganisms in the oral cavity, Streptococcus mutans, which may be hereinafter simply referred to as S. mutans, is considered as one of the pathogenic bacteria for dental caries. In addition, the periodontitis which is an inflammatory disease of a periodontal tissue is said to be developed due to the bacteria in the oral cavity. In general, if the bacteria causing dental caries as described above are adhered to the surfaces of the teeth, the dental plaques are formed, which are said to be causative of various diseases in the oral cavity, such as dental caries and periodontal diseases.
For this reason, a dental composition for oral use which applies the technique of coating surfaces of the teeth with a specified drug or a polymer, thereby suppressing the adhesion of bacteria, to inhibit the formation of plaques has been proposed. Among them, a composition containing a cationic bactericidal agent, such as cetyl pyridinium chloride, benzethonium chloride, or chlorhexidine, the composition having a high bactericidal activity against bacteria in the oral cavity has been well used for this purpose. However, the cationic bactericidal agent as described above cannot be detained on the surfaces of the teeth for a long time when used alone, so that the agent has disadvantages such as lowered sustainability of the effects, thereby making it poor in actual use.
In order to solve the problems as mentioned above, for example, a technique of accelerating an adsorption action of a bactericidal agent by using a lower alkyl ester of an N-long-chained acyl basic amino acids in combination with a cationic bactericidal agent (see, for example, Patent Publication 1), a technique of using a polyphosphoric acid and a polyglycerol fatty acid ester in combination with a cationic bactericidal agent (see, for example, Patent Publication 2), and a technique of using a polymer of ammonium dimethyldiallyl chloride as a cationic bactericidal agent (see, for example, Patent Publication 3) have been disclosed.    Patent Publication 1: Japanese Patent Laid-Open No. Hei 9-286712    Patent Publication 2: Japanese Patent Laid-Open No. 2006-117574    Patent Publication 3: Japanese Patent Laid-Open No. Hei 9-175965